Printing Advancements/Dot Dispensing

Integrated Dot Dispensing (Option)

Milara has just teamed up with Asymtek to reintroduce dot dispensing capabilities in its new TD2929 system, employing the Piezo electric dot dispensor using the SV-100 slider valve. This unit boasts the following:

 

Piezo Electric Dot Dispensor

Figure 1: Dot diameter 256 μm

(+/-8.4% at 3σ)

Features and Benefits:

  • Up to 20% faster than auger dispensers
  • 20000 dots per hour (1 mm grid)
  • Dot & Line deposition capability
  • Compatible with lead free and no clean solder pastes
  • Small diameter paste dispensing for passive components (0402, 0201...)
  • Ideal for BGA re-work, when screen printing is not an option

 

  • Dots<300 μm with type 4, 5 & 6 pastes
  • Compatible with Silver filled Epoxies
  • Compatible with off-the-shelf needles
  • Resistant to plugging
  • Complements screen printing when SMT component mix requires large variation in dot sizes or difficult to print dot sizes

 

The inspection camera gantry contains the SV-100 dispensing valve mounted.(Figure 2) This assembly also incorporates a laser real-time feedback displacement sensor that automatically adjusts the Z height of the dispenser tip to ensure dynamic consistency during the dispensing cycle (Figure 3).

 

Inspection camera gantry

Figure 2: Inspection

camera gantry

Laser eal-time feedback displacement sensor

Figure 3: Laser real-time feedback displacement sensor

Innovations in Wafer Printing

With the advent of wafer bumping , Milara was tasked to conduct print testing directly to the under bump metallurgy (UBM) (Figure 4). This process would eliminate the costly process of wafer bumping which requires several heavily chemically-oriented steps to produce the required valleys or “divots” around the UBM which is then filled by the wafer bumping printing process (Figure 5). After bumping, inspection and reflow (Figure 6), the wafer is then subjected to another chemical stripping process to remove the devoted dry layer and ultimately present the solder bumps for the flip-chip process.

 

Vibration Squeegee Bump Print

Figure 4: Vibration Squeegee Bump Print

Post Reflow Oven

Figure 5: Post Reflow Oven

Laser eal-time feedback displacement sensor

Figure 6: X-ray Inspection Post Reflow

MiniTouch-Wafer-Bumper

Figure 7: MiniTouch Wafer Bumper



Back in the late 90's this process was developed by Flip Chip, Kuliche and Soffa in cooperation with Milara to create a system that would print the wafers. Milara developed the MiniTouch Wafer printing system (Figure 7) to be commissioned into packaging companies such as Advanced Semiconductor Engineering, Silicon Precision, Amkor, Dephi-Delco and Unisem.

Milara was also tasked to see if in fact we could print directly to the UBM's using standard stencil printing technology. Working with one of our stencil fabricators, they had suggested using a Kapton material based stencil. Figure 8 shows the results! The image shows the overall quality of the Kapton stencil technology we have employed for this application.

 

Wafer post direct printing

Figure 8: Wafer post direct printing

Figure 9 is an overhead view.

Wafer post direct printing

Figure 9: Overhead view of the wafer

Figures 10 and 11 show the printed bumps in varied magnification. As one can see, the bumps appear uniform and geometrical with NO missed UBM prints. More testing will be conducted by Milara this year to generate more conclusive data as to the viability of this direct wafer printing method.

 

Overview of Kapton wafer print

Figure 10: Overhead view of the wafer

 

360X magnification of wafer print

Figure 11: 360X magnification of wafer print

Mask Aligner Products

Mask Aligners combine ‘open architecture’ modular design with precision alignment and exposure features. They support vacuum, contact and proximity printing and handle partial and whole substrates up to 200mm (8”) diameter or up to 6” square. 

This versatility made our mask aligners the choice of manufacturing facilities, R&D Centers and university programs around the world, employed by them for a wide range of technologies.

Scalable from R&D to HVM by adding Robot Upgrade; same process recipes from R&D to HVM.

 

Inspection camera gantry

Figure 12: NXQ4006 Mask Aligner

Laser eal-time feedback displacement sensor

Figure 13: NXQ8006 Mask Aligner

Laser eal-time feedback displacement sensor

Figure 14: Automated Wafer Loading on NXQ8006 Mask Aligner